Define complex lipids and write the structure of nucleotide and nucleoside?

Hint: The field of chemistry which deals with the chemical processes regarding the living organisms, is called biochemistry.
The basic building blocks of all living organisms are nucleic acids, which are of two types, Deoxyribonucleic acid $(DNA)$ and Ribonucleic acid $(RNA)$.

Complete step by step answer:
Complex lipids: heterogeneous groups of compounds including fats, oils, steroids, waxes and related compounds which are related more by their physical than by their chemical properties are called lipids.
Complex lipids are esters of fatty acid containing groups in addition to alcohol and fatty acids. Example- phospholipid, glycolipids etc.
The structure of nucleotide and nucleoside: we know that there are mainly two types of nucleic acids
1.Deoxyribonucleic acid $(DNA)$ and
2.Ribonucleic acid $(RNA)$
The basic difference between the two classes of nucleic acid is that the deoxyribonucleic acid has a double helical structure, where both the strands interact with each other through hydrogen bonding. While in the case of ribonucleic acid it has just one strand.
Since nucleic acids are long chain polymers of nucleotides. So they are also called polynucleotides.
A unit formed by attachment of a base to the $1'$ position of sugar is known as nucleoside. In nucleosides, the sugar carbons are numbered. When nucleoside is linked to phosphoric acid at $5'$ position of sugar moiety, we get a nucleotide.

Given above are the structures of nucleotide and nucleoside. As we can see they differ from each other because of a phosphoric group.

Note: The basic difference between nucleotide and nucleoside is the presence of a phosphoric group in the nucleotide. The complex lipids are the lipids or fatty acids which contain additional functional groups like phosphorus etc.